Electric power source

ABSTRACT

An electric generator operated by means of flow of fluid against a diaphragm to which a piezo-electric material is secured. The fluid flows into a cavity through an orifice and the fluid exhausts from the cavity between the diaphragm and a closely spaced annular shoulder. Pressure variations within the cavity caused by flexure of the diaphragm creates a self-sustained diaphragm vibration for generation of electricity by the piezoelectric material.

United States Patent Sinker et a1.

[is] 3,665,226 [451 May 23, 1972 154] ELECTRIC POWER SOURCE [72] Inventors: Robert A. Sinker, Beverly Hills; George L.

Williams, Santa Monica, both of Calif.

[73] Assignee: Hughes Aircraft Company, Culver City,

Calif.

[22] Filed: July 13, 1970 [21] Appl. No.: 56,216

Related US. Application Data [63] Continuation of Ser. No. 725,726, May 1, 1968, abandoned.

[52] US. Cl. ..310/8.3, 310/82, 310/85,

310/87, 310/9.1, 73/194 B, 73/194 E, 181/.5 AG,

[51] Int. Cl ..H04r 17/00 [58] Field of Search ..310/8, 8.2, 8.3, 8.5, 8.6, 310/817, 9.1, 9.4; 73/194 R, 194 B, 194 E; 322/2;

181/.5 AG; 340/116, 117, 10, 15, 17; 102/70.2 A;

2,928,409 3/1960 Johnson et al ..310/8.l 3,021,708 2/ 1962 November et a1. 73/ 1 94 3,144,767 8/1964 Testerman et a1. ..73/194 3,171,915 3/1965 Johnson 137/81.5 X 3,182,686 5/1965 Zilberfarb 137/815 X 3,264,861 8/1966 Miles 3 l0/8.6 X 3,307,052 2/1967 Neilson et al.. ..310/8 3,354,327 11/1967 Benson ..310/8.7 3,519,009 7/1970 Rubin ..137/81 5 Primary Examiner-L. T. Hix Assistant Examiner-Mark O. Budd Attorney-James K. Haskell and Lewis B. Sternfels 57 ABSTRACT An electric generator operated by means of flow of fluid against a diaphragm to which a piezo-electric material is secured. The fluid flows into a cavity through an orifice and the fluid exhausts from the cavity between the diaphragm and a closely spaced annular shoulder. Pressure variations within the cavity caused by flexure of the diaphragm creates a selfsustained diaphragm vibration for generation of electricity by the piezo-electric material.

7 Claims, 3 Drawing Figures ELECTRIC POWER SOURCE This application is a continuation of copending application, Ser. No. 725,726, filed May I, 1968, now abandoned, for Electric Power Source.

The present invention relates to a source for producing electrical power and, more particularly, to such a source obtained from vibrating a piezo-electric material by impacting a fluid thereon.

The flow of-a gaseous fluid, such as air, may be used in various ways to produce a vibration in a cavity or in a mechanical structure. In whistles and in certain musical instruments, such as the flute, the flow of air over a sharp edge produces a turbulent condition which is reinforced by a resonant cavity to create an oscillation in the air column and a musical tone. In other devices a reed is used, mounted within an opening in such a manner that motion of the reed modulates the flow through the opening. The pressure variations set up by this valving action of the reed causes a sustained vibration of the reed and the modulated flow produces a musical tone. In certain reed instruments, such as the harmonica and the accordion, the tone produced depends upon the physical characteristics of the reed itself. Each reed produces only one tone and a multiplicity of reeds is required for a range of tones. In other reed instruments, such as the clarinet, a single reed is used together with a resonant cavity. An interaction between the reed and the oscillation in the air column of the cavity causes the motion of the reed to be governed by the length of the cavity, controlled by covering and uncovering openings. In this way a range of tines may be produced by a single reed.

In another example, a jet of air directed axially against the end of a reed will produce an oscillation of the reed at its natural frequency due to a turbulence in the air flow.

The present invention utilizes still another principle to produce a mechanical vibration of a flexible member to which a piezo-electric material is secured. When the piezo-electric material vibrates with the flexible member, electrical energy is produced. This principle utilizesthe flow of a fluid against the flexible member to produce the vibration and is described in detail hereinafter.

It is, therefore, an object of the present invention to provide a source of electrical power.

Another objectis the provision of such an electrical power source by the combination of a piezo-electric material and a motion produced by gaseous fluid flow.

Another object is to provide electrical power from a piezoelectric material through flexure produced by gaseous fluid flow utilized in an improved manner to provide increased power from a given flow offluid.

Other aims and objects, as well as a more complete understanding of the present invention will appear from the following explanation of exemplary embodiments and the accompanying drawings thereof, in which:

FIG. 1 is an elevational view in section of the present invention;

FIG. 2 is a view of the invention taken along lines 2-2 of FIG. I; and

FIG. 3 is a cross-section of the present invention taken along lines 3-3 of FIG. 1.

Accordingly, a source of electrical power comprises a body 12 having a flange 14. Body 12 is provided with a through bore 16 having a step in diameter to produce a small diameter bore 18 of smooth interior and an internally threaded large diameter bore 20. An attachment 24 threadedly engages bore 20 and is provided with a nose 26 which fits closely within narrow bore 18. An inlet bore 28 extends through attachment 24 and is provided with an orifice 30 formed by end wall 32 of the attachment for control of the inlet flow to device 10. A fluid conduit 34 threadedly engages the other end 36 of the attachment for supply of a fluid from a source. A pressure gage tap 38 extends from bore 28 to a pressure gage 40 to detect the pressure of the fluid entering source 10.

Exhaust from the source is effected by a plurality of exhaust ports 22 extending through flange 14 and spaced around the outer circumference of body l2.

An annular shoulder 42 is provided at the outlet end of bore 18 and defines with end wall 32 of nose 26 a chamber or recess 44. The recess is partially closed off by a flexible diaphragm 46 which is affixed in position at its outer edges between flange l4 and an end plate 48. Annular shims 50 and 52 are placed on both sides of the edges of the diaphragm to insure free support of diaphragm 46. Shims 52, between diaphragm 46 and flange 14, provide a proper spacing for a gap 54 between the diaphragm and annular shoulder 42. In order to provide the proper flexibility of the diaphragm, the diaphragm is formed of a suitable material such as a berylliumcopper alloy.

A piezo-electric disc 56 is cemented and grounded to diaphragm 46 in electrical contact therewith and a lead 58, connected to piezo-electric disc 56, extends through a hole 60 in end plate 48 for connection to a device to be electrically driven by source 10. A second lead 62 extends from device 10 to complete the power source.

A plurality of holes 64 are formed in flange 14 and end plate 48 for reception of bolts therethrough in order to secure the diaphragm 46 in place. It is to be understood, however, that flanges 14 and 48 may be made unitary when the dimensions of gap 54 have been predetermined and that attachment 24 and body 12 may also be made unitary when the dimensions of chamber 44 have been predetermined.

The proper operation of the invention is primarily dependent upon the cooperation among shoulder 42, chamber 44, orifice 30, and gap 54 between diaphragm 46 and the annular shoulder. The width of the shoulder is important since this width influences the amount of damping in the movement of diaphragm 46 and, since a minimum of damping is desired, the width of the shoulder is adjusted accordingly. In addition, the size of cavity 44, along with the dimensions of gap 54 and of orifice 30, bears a direct relationship as to the maximum desired flexure of diaphragm 46. In general, since shoulder 42 and orifice 30 are already formed, attachment 24 is moved back and forth by means of the threaded engagement with body 12 to vary the length and, hence, the volume of cavity 44.

Assuming proper adjustment of all parts, air or other fluid is brought to one side of diaphragm 46 through orifice 30 and into cavity 44, the fluid being supplied through conduit 34. The fluid escapes through gap 54 between the diaphragm and annular shoulder 42. When the above adjustments are suitably made, an instability occurs as the air passes between the shoulder and the diaphragm. At first, the air causes diaphragm 46 to move and to open gap 54 thus permitting a large volume of air to escape chamber 44. The pressure within the chamber consequently drops and the diaphragm thereafter moves to close gap 54, thus permitting pressure within chamber 44 to increase. The diaphragm again moves to open gap 54. Therefore, flexure of the diaphragm changes the pressure within cavity 44 and, hence, the cavity pressure is a function of the in-flow through the orifice and the outflow through gap 54. Vibration of the diaphragm produces a pressure fluctuation in the cavity with a phase shift depending upon the volume of the cavity. When adjustments are properly made, this phase shift is in the direction to produce self-sustained vibration of the diaphragm.

Although the invention has been described with reference to a particular embodiment thereof, it should be realized that various changes and modifications may be made therein without departing from the spirit and scope of the invention.

What is claimed is:

l. A source of electrical power having spaced inlet means and outlet means and comprising a flexible member, a piezoelectric element secured to said member and flexible therewith, said member and said element having a natural frequency in flexure, a source of fluid coupled to said inlet means, and pressure variation means including said member, a resonant cavity, and exit means coupled to said outlet means, said pressure variation means positioned between said outlet means and said inlet means and generating pressure variations in response to flow of the fluid to cause vibration of said member and said element at the natural frequency.

2. A source of electrical power comprising a body having an inlet and an outlet, said outlet being distinct from said inlet; a flexible diaphragm supported at the edges thereof in said body; a piezo-electric element secured to said diaphragm and flexible therewith; a source of fluid; and pressure variation means positioned between the inlet and the outlet; said pressure variation means including said diaphragm, a chamber bounded by the outlet and the inlet, an annular shoulder on said body at the outlet of said chamber and spaced closely from said diaphragm, and orifice means at the inlet of said chamber and coupled to said fluid source whereby flow of the fluid causes changes in pressure of said pressure variation means including self-sustained vibration of said diaphragm and said element.

3. A source of electrical power comprising a body provided with inlet means connected to a source of fluid and terminat ing in orifice means; a flexible member secured at its periphery to said body and spaced from said orifice means; a piezoelectric element secured to said member and flexible therewith; a chamber including said flexible member disposed in said body and opening to said inlet means through said orifice means; an annular shoulder formed on said body and spaced from said flexible member and from said orifice means to provide termination means having variable opening means for said chamber; and exhaust means coupled to the termination means; said member and said element vibrating in response to variations of fluid pressure in said chamber as the fluid flows through said orifice means into said chamber and past the termination means between said shoulder and said flexible member.

4. A source as in claim 3 wherein said inlet means comprises an attachment moveable in said body for adjustment of the size of said chamber.

5. A source of electrical power comprising pressure resonant cavity means, a flexible member forming a wall for said cavity means, a piezo-electric element secured to said member and flexible therewith, a source of fluid, gap means adjacent said member and terminating said cavity means for exit of the fluid, orifice means as said source of fluid and forming an opening into said cavity means, said gap means, said orifice means and said cavity means being so dimensioned as to enable the provision of variations in pressure in said cavity and concurrent self-sustained vibration of said member and said element upon the flow of said fluid from said source, through said orifice means and cavity means, and out past said gap means.

6. A source as in claim 5 wherein said gap means comprises an annular shoulder spaced closely from said member.

7. A source as in claim 6 wherein said flexible member com prises a diaphragm supported at the periphery thereof. 

1. A source of electrical power having spaced inlet means and outlet means and comprising a flexible member, a piezo-electric element secured to said member and flexible therewith, said member and said element having a natural frequency in flexure, a source of fluid coupled to said inlet means, and pressure variation means including said member, a resonant cavity, and exit means coupled to said outlet means, said pressure variation means positioned between said outlet means and said inlet means and generating pressure variations in response to flow of the fluid to cause vibration of said member and said element at the natural frequency.
 2. A source of electrical power comprising a body having an inlet and an outlet, said outlet being distinct from said inlet; a flexible diaphragm supported at the edges thereof in said body; a piezo-electric element secured to said diaphragm and flexible therewith; a source of fluid; and pressure variation means positioned between the inlet and the outlet; said pressure variation means including said diaphragm, a chamber bounded by the outlet and the inlet, an annular shoulder on said body at the outlet of said chamber and spaced closely from said diaphragm, and orifice means at the inlet of said chamber and coupled to said fluid source whereby flow of the fluid causes changes in pressure of said pressure variation means including self-sustained vibration of said diaphragm and said element.
 3. A source of electrical power comprising a body provided with inlet means connected to a source of fluid and terminating in orifice means; a flexible member secured at its periphery to said body and spaced from said orifice means; a piezo-electric element secured to said member and flexible therewith; a chamber including said flexible member disposed in said body and opening to said inlet means through said orifice means; an annular shoulder formed on said body and spaced from said flexible member and from said orifice means to provide termination means having variable opening means for said chamber; and exhaust means coupled to the termination means; said member and said element vibrating in response to variations of fluid pressure in said chamber as the fluid flows through said orifice means into said chamber and past the termination means between said shoulder and said flexible member.
 4. A source as in claim 3 wherein said inlet means comprises an attachment moveable in said body for adjustment of the size of said chamber.
 5. A source of electrical power comprising pressure resonant cavity means, a flexible member forming a wall for said cavity means, a piezo-electric element secured to said member and flexible therewith, a source of fluid, gap means adjacent said member and terminating said cavity means for exit of the fluid, orifIce means as said source of fluid and forming an opening into said cavity means, said gap means, said orifice means and said cavity means being so dimensioned as to enable the provision of variations in pressure in said cavity and concurrent self-sustained vibration of said member and said element upon the flow of said fluid from said source, through said orifice means and cavity means, and out past said gap means.
 6. A source as in claim 5 wherein said gap means comprises an annular shoulder spaced closely from said member.
 7. A source as in claim 6 wherein said flexible member comprises a diaphragm supported at the periphery thereof. 